JP2001164494A - Paper for newspaper used for offset printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper for the newspaper used for an offset printing, excellent in printing non-transparency, and having an excellent color-printing quality. SOLUTION: This paper for the newspaper used for the offset printing is provided by applying a surface-treating agent containing a pigment and an adhesive as main components over a stock paper, especially using satin white as the above pigment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to newsprint paper for offset printing having excellent print opacity and excellent color print quality.

[0002]

2. Description of the Related Art In recent years, newspaper printing has rapidly shifted to offset printing, increased in color (multicolor), and increased in speed. As a result, even for paper as a printing medium, more excellent color printing suitability has been achieved. And newsprint having printing workability are required. By the way, in offset printing, a paper having a strong surface strength is required because a printing ink having a relatively high tack is used. Also, to use dampening water,
Paper with strong water resistance on the surface is required. Incidentally, when a paper having a low surface strength or a paper having low or no water resistance is used, troubles such as generation of so-called blurring on a printing surface occur due to accumulation of paper dust on a blanket or mixing with ink.

Further, with the recent reduction in weight of newsprint, high opacity after printing on the paper is required. In order to increase the opacity of paper, hydrated silicic acid (commonly referred to as white carbon), inorganic pigments such as titanium oxide and talc, and organic pigments such as urea-formaldehyde resin have been widely used as papermaking fillers. Was. Above all,
White carbon is the most widely used because of its low cost and opacity effect. In general, white carbon has a very small primary particle size and relatively uniform size, but in most cases forms secondary aggregates, and the particle size at the time of use ranges from small particles to large particles It is widely distributed. When such a filler is added to papermaking pulp to make paper, particles in the small particle size region having an effect on opacity are extremely poorly retained on the paper, and in order to obtain a sufficient effect, increase the addition ratio. It is necessary.

[0004] On the other hand, these fillers tend to leach out of the paper layer easily by the dampening solution used in the printing process at the time of offset printing when the addition ratio is increased, and the main component of the paper powder piled on the blanket. It has become one of. In addition, the high proportion of deinked waste paper pulp (hereinafter, referred to as DIP), which is considered to be important in the environment, is less opaque than mechanical pulp such as GP, RGP, and TMP. It is extremely difficult to achieve both improvement in opacity and high mixing ratio of DIP.

[0005] In order to cope with such disadvantages of newsprint paper for offset printing, conventionally, the surface of the newsprint has starch,
It is common practice to apply an aqueous composition containing PVA, polyacrylamide, or the like as a surface treatment agent. Although these surface treatment agents have the function of improving the paper surface strength and adhering fine fibers and fillers on the paper surface to pulp fibers, etc., the surface of the newsprint when exposed to moisture is tacky (hereinafter referred to as Nippari property). ), Resulting in running troubles such as sticking to a blanket during printing, wrinkles, and paper breakage.

In view of the above, various methods have been conventionally proposed for newsprint for offset printing in order to obtain high opacity and to obtain good surface strength. For example, the base paper surface has an oil absorption of 65 cc / 100 g-
A method of increasing opacity by providing a coating layer having a filler of 150 cc / 100 g (JP-A-1-17469)
No. 7), a pigment and a specific latex (SB
R) a composition containing a water-soluble adhesive as a main component in an amount of 0.3 to 3;
g / m ² coating method (JP-A-2-19595), and a method in which a specific amount of an organic pigment such as a plastic pigment or a binder / pigment is contained in a binder containing starch or latex (JP-A-5-1995). -263
394) and the like have been proposed. However, 4
5 g / m ² or less of low rice tsubo product or recycled paper pulp compounding ratio of 40
In the case of base paper having a weight percent or more, it has not yet been possible to obtain satisfactory results in terms of improving opacity, achieving compatibility with color printing, and eliminating (reducing) blanket piling.

[0007]

DISCLOSURE OF THE INVENTION The present inventors have been keen to obtain a lightweight paper (excellent in opacity) which has a high proportion of used paper and excellent offset printing suitability as newsprint for offset printing. Repeated research. As a result, the present invention provides newsprint paper for offset printing desired by the present invention by using satin white as a surface treatment agent applied to the surface of the paper.

[0008]

SUMMARY OF THE INVENTION According to the present invention, in a newsprint for offset printing obtained by applying a surface treatment agent containing a pigment and an adhesive as main components on a base paper and drying, a satin white is used as the pigment. This is newsprint for offset printing. Further, the present invention includes the following embodiments. That is, the offset printing wherein the content of satin white is 50% by weight or more based on all the pigments and the amount of the surface treatment agent applied is 0.05 to 1.0 g / m ^{2 on} one side by dry weight. Newspaper.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, starch, polyvinyl alcohol (hereinafter referred to as PVA), polyacrylamide, and the like are conventionally applied to the surface of newsprint for offset printing. All of these external coating agents (surface treatment agents) are effective in suppressing the generation of paper dust, but have poor water resistance and are liable to cause blanket piling and nepari problems. Furthermore, when these surface treatment agents are used in a large amount, it is difficult to prevent the printing ink from penetrating into the paper surface, so that there is a disadvantage that ink absorption unevenness (color unevenness on the printing surface) due to coating unevenness easily occurs during color printing. I have.

The combination with kaolin, calcium carbonate, etc., which has been conventionally used in the production of general coated paper,
Although the nepari property of PVA or the like can be reduced, it is not sufficient to obtain newsprint having the high opacity desired by the present invention. That is, the amount of rice tsubo (coating amount) that is increased by applying the above-described ordinary pigment is
It is adjusted by lowering the rice tsubo of the pulp fiber base paper, but it has been found that the reduction in opacity due to the reduction of the base pulp (pulp fiber) rice tsubo cannot be covered by ordinary pigment coating. .

On the other hand, titanium dioxide, which is known as a pigment having a high opacity, can obtain better opacity and improve the nepari property as compared with the case where other pigments are used. The compatibility with the agent was poor, and agglomerates were easily formed during coating, and stable operation was difficult. Also,
At the time of offset printing, the blanket had a problem that it was stained white and was difficult to wipe.

It should be noted that hydrated silicic acids such as white carbon and amorphous silica have high oil absorption, so that by coating them, good opacity after printing can be obtained, but the surface strength is low. There is a problem that paper powder is piled during printing because of weakness.

In the present invention, the surface treatment agent
Chin White is used for starch, polyacrylamide, polyvinyl
By using it together with an adhesive such as alcohol.
Increases the opacity of the paper and eliminates ink absorption unevenness.
Good printing surface can be obtained, and paper dust and nappari property etc.
Can reduce printing and improve printing workability.
Has features. This satin white is coated for general printing
It is commonly used in the paper field. And its use eyes
The target is to increase the gloss of the coated surface, to deposit the ink, and to increase the ink gloss.
It is used for the purpose of improving the quality. Meanwhile, Sachin
Since white has poor dispersion stability of pigment particles, white
100 parts by weight of pigment, in a ratio of 1 to 20 parts by weight
It is generally used. On the other hand, in the present invention,
The amount of tin white used is based on 100 parts by weight of the total pigment.
Used at 50 parts by weight or more, more preferably at 80 parts by weight or more
It is necessary to. In that case, a high concentration (for example, 50
(% By weight or more) is difficult to prepare as a surface treatment agent
However, as in the present invention, the solid coating amount is 1 g / m ^Two Below
Low concentration, for example, 20% by weight or less.
The concentration can be sufficient. In addition, the combination of Sachin White
Opaque if less than 50% by weight, based on total pigment
Improvement of ink absorption and uneven ink absorption
There is a possibility that it may become unfavorable.

The reason why satin white has the effect of improving opacity and the effect of neppari resistance and blanket piling is not necessarily clear, but is presumed as follows. That is, usually, satin white is acicular particles, and has a property of becoming unstable and aggregating in a pH range of 10 or less. For this reason, when a surface treatment agent containing satin white is applied to the paper surface (usually acidic), gelation of the coating layer is promoted due to a decrease in pH due to contact with the paper surface, and needle-like satin white is immobilized. It is thought that the napping property exhibited by the adhesive is reduced because of the phenomena that are left on the paper layer surface due to the formation of a phenomena, and high printing opacity is exhibited because the ink is adsorbed at the part close to the paper surface during printing Can be

Next, a pigment (mainly satin white)
The adhesive used in combination with is not particularly limited, for example, starches such as enzyme-modified starch, oxidized starch, cationized starch, carboxymethyl cellulose, methyl cellulose, water-soluble cellulose compounds such as hydroxyalkyl cellulose, PVA compounds And polyacrylamides, synthetic latexes such as styrene-butadiene copolymer latex, and methyl methacrylate-butadiene copolymer latex. Among them, starches and polyacrylamides are particularly preferably used because of their good compatibility with Satin White. It is particularly preferable to maintain the pH of the surface treatment agent at 10 to 12 so that coating can be performed with a stable viscosity. In addition, in the surface treatment agent, in addition to the above-mentioned satin white and the adhesive, a surface sizing agent, an antifoaming agent, a preservative, a thickener, etc. which are generally used in the papermaking field and the coated paper manufacturing field are appropriately used. Is done.

Further, pigments for coated papers used in the field of production of general coated papers, for example, kaolin, clay, calcined kaolin, amorphous silica, zinc oxide, aluminum oxide, aluminum hydroxide, calcium carbonate, titanium dioxide Inorganic pigments such as aluminum silicate, magnesium silicate and magnesium carbonate, and organic pigments such as plastic pigments can be appropriately mixed and used. In this case, the amount of the satin white pigment should be 50% by weight or more, preferably 80% by weight or more of the total pigment, as described above, in order to improve opacity or to eliminate uneven ink absorption. Considering that point, the above-mentioned pigments should be used in combination.

The ratio of the pigment containing satin white as a main component is 5 parts by weight based on the total adhesive in the surface treating agent.
It should be adjusted between 0 and 300% by weight. By the way, 5
If the amount is less than 0% by weight, the effect of reducing the nepari property and the effect of improving the opacity are not sufficient. On the other hand, if the amount exceeds 300% by weight, paper dust may be generated. The surface treatment agent thus obtained is adjusted to a solid content concentration of 1 to 20% by weight, and coated on newsprint base paper. The amount of coating at that time is usually in the range of 0.05 to 1.0 g / m ² , preferably 0.1 to 0.6 g / m ^{2, on} a dry weight basis, on both sides of the base paper and dried. By the way, when it is less than 0.05 g / m ² ,
Sufficient opacity is difficult to obtain, while if it exceeds 1.0 g / m ² , the nap-parity increases, and there is a concern that sticking to a blanket and the like may occur.

As the base paper for newsprint in the present invention,
The main pulp fibers are chemical pulp (NBKP, LBKP, etc.), mechanical pulp (GP, CGP, RGP, PGW, TMP, etc.), deinked waste paper pulp (DIP), etc. Alternatively, it is mixed at an arbitrary ratio to prepare a stock, and then supplied to papermaking. Fillers such as white carbon, clay, amorphous silica, talc, titanium oxide, and calcium carbonate are added to the stock. In addition, if necessary, generally known and commonly used papermaking chemicals such as a paper strength enhancer, a retention improver, a sizing agent such as a strengthened rosin sizing agent and an emulsion sizing agent, a water-proofing agent, a coloring agent, or an ultraviolet ray inhibitor are added. Then, the paper is made by a publicly known paper machine. And as the basis weight of the base paper,
Although not particularly limited, in the case of the present invention, 30 to 4
When applied to a thin material such as 2 g / m ^{2, the} effect of improving the opacity is remarkable, which is a preferable embodiment.

The above-mentioned base paper is coated and dried with a surface treating agent which is a feature of the present invention. The coating apparatus in this case is not particularly limited. A ring size press, a rod metaling size press, a gate roll coater, a blade coater, a bar coater, a rod blade coater, an air knife coater, a curtain coater and the like are appropriately used.

[0020]

The present invention will be specifically described below with reference to examples. Of course, the present invention is not limited to these examples. Parts and% in the examples are parts by weight and% by weight, respectively, unless otherwise specified.

Example 1 Papermaking of base paper A pulp slurry obtained by mixing 10 parts of softwood kraft pulp, 30 parts of thermomechanical pulp, 20 parts of ground pulp, and 40 parts of DIP was defibrated with a refiner, and freeness was 100 ml / csf (Canada). Pulp slurry prepared to standard freeness) has an average particle size of 23μ
The white carbon m was added in an amount of 1% per pair bone dry pulp as a filler, performs paper by gap former type paper machine to obtain newsprint base paper for the basis weight 40 g / m ^2.

● Coating of surface treatment agent As an adhesive, starch dissolved in hot water (trade name: ACE A)
/ Oji Corn Starch Co., Ltd.) in a solid content of 100 parts and a pigment having a BET specific surface area of about 19 m ² / g, Sachin White (trade name: Sachin White BL / Shiroishi Kogyo Co., Ltd.) 10
After mixing and stirring 0 parts, the mixture was diluted with water, and the pH was adjusted to 11 by adding caustic soda to obtain a surface treatment agent having a solid content of 10%. After applying the surface treating agent to both sides of the base paper (40 g / m ^{2 of} rice basis) obtained above using a gate roll coater so that the dry weight per side is 0.6 g / m ^2, and then drying. A calender was passed under the conditions of a linear pressure of 130 kg / cm to obtain newsprint paper for offset printing having an air-dry basis weight of 41.2 g / m ² .

Example 2 In the preparation of the surface treating agent of Example 1,
PVA (trade name: R-11) instead of starch (Ace A)
30 / Kuraray Co., Ltd.) Newspaper for offset printing was obtained in the same manner as in Example 1 except that 100 parts were used.

Example 3 In the preparation of the surface treating agent of Example 1, instead of Sachin White (Sachin White BL), Sachin White having a BET specific surface area of about 8 m ² / g (trade name: Sachin White B / Shiroishi Kogyo) Example 1 except for changing to 100 copies
Newsprint paper for offset printing (basis weight 41.6)
g / m ² ). Incidentally, the coating amount at this time was 0.8 g / m ² per one side.

Example 4 In the preparation of the surface treating agent of Example 1, the amount of the pigment, satin white, was changed from 100 parts to 60 parts, the concentration of the surface treating agent was 12%, and the coating amount was one sided. Per day, except that it was changed to 0.9 g / m ² , in the same manner as in Example 1, except that newsprint paper for offset printing (41.8 g / m ² basis weight) was used.
² ) Got it.

Example 5 In the preparation of the surface treating agent of Example 1, polyacrylamide (trade name: NP10 / Mitsui Chemicals) was used instead of starch.
Newspaper for offset printing (basis weight 41.0 g / m ² ) was obtained in the same manner as in Example 1 except that 100 parts were used.
At this time, the coating amount was 0.5 g / m ² per one side.

Comparative Example 1 In the preparation of the surface treating agent of Example 1, titanium dioxide (trade name: CR-5) was used instead of the pigment, satin white.
0 / Ishihara Sangyo Co., Ltd.) Newspaper for offset printing was obtained in the same manner as in Example 1 except that 100 parts by weight was used.

Comparative Example 2 In the preparation of the surface treating agent of Example 1, sedimentable calcium carbonate (trade name:
Except for using 100 parts by weight of Brilliant S15 / Shiroishi Kogyo Co., Ltd., newsprint paper for offset printing (basis weight 41.6 g / m ² ) was obtained in the same manner as in Example 1. Incidentally, the coating amount at this time was 0.8 g / m ² per one side.

Comparative Example 3 In the preparation of the surface treating agent of Example 1, primary kaolin (trade name: UW-
90 / Engelhard Co.) was used in the same manner as in Example 1 except that 100 parts by weight of offset newsprint paper (basis weight 41.6 g / m ² ) was obtained. At this time, the coating amount was 0.8 g / m ² per one side.

Comparative Example 4 Newspaper for offset printing (basis weight 40.8 g / m ² ) was obtained in the same manner as in Example 1 except that no pigment was added in the preparation of the surface treating agent of Example 1. Was. At this time, the coating amount was 0.4 g / m ² per one side.

The newsprint for offset printing obtained in the above Examples and Comparative Examples was subjected to the following quality tests, and the obtained results are shown in Table 1. [Quality test] ● Opacity: Measured in accordance with ISO2471.

● Ink absorption unevenness: Using an offset printing machine (Komori SYSTEM C-20), four-color printing was performed, and the ink density unevenness in the indigo / red overlapping color portion was visually determined. : A uniform image with almost no ink density unevenness. Δ: An image in which unevenness in ink density was observed and was slightly uneven.

● Blanket paper powder piling: Using an offset printing machine (Komori SYSTEMC-20), after printing continuous 5000 copies by four-color printing, visually observe the degree of paper dust accumulation in the blanket non-image area. Was determined. : No generation of paper dust was observed. Δ: Generation of paper powder is slightly observed. ×: A lot of paper powder is deposited on the blanket.

● Neppari (blanket adhesiveness)
: Cut two newspaper printing paper samples into appropriate size, immerse them in water for 10 seconds, and then quickly bring the two papers together,
After passing through a calender at a linear pressure of 100 kg / cm and drying at room temperature for 24 hours, the peel strength of the two sheets of paper was measured using a tensile tester. The higher the value, the stronger the tackiness.

[0035]

[Table 1]

As is clear from Table 1, the newsprint obtained in Examples according to the present invention has excellent opacity and color printing quality, has no blanket paper powder piling or sticking of blanket, and has good printing workability. It was excellent.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Kazuhiro Nojima 4-3-1 Jokoji, Amagasaki-shi, Hyogo F-term in the Oji Paper Co., Ltd. Amagasaki Research Center (reference) 4L055 AG08 AG16 AG17 AG47 AG64 AG72 AH02 AH37 AJ04 EA14 EA32 FA12 GA16 GA19

Claims (2)

[Claims] (1) offset printing, wherein a satin white is used as the pigment in offset printing newsprint obtained by applying a surface treatment agent containing a pigment and an adhesive as main components on a base paper and drying the coated paper; Newsprint. 2. The content of satin white is at least 50% by weight based on all pigments, and the amount of the surface treating agent applied is 0.05 to 1.0 g / m ^{2 on} one side by dry weight. Item 4. Newsprint paper for offset printing according to Item 1.